This invention relates generally to the treatment of diseased arteries. More specifically, the invention provides for the internal irradiation of a blood vessel preceding or following an angioplasty or atherectomy procedure, or the implantation of a stent.
Percutaneous transluminal angioplasty is an exemplary procedure in treating peripheral vessels or the coronary vessels surrounding the heart. During angioplasty, a catheter having an expansible distal end, usually in the form of a balloon, is positioned in a lumen of a blood vessel with the distal end disposed within a stenotic atherosclerotic region of the vessel. The expansible end is then expanded to dilate the vessel and restore adequate blood flow through the diseased region.
While angioplasty has gained wide acceptance, it continues to be limited by two major problems, abrupt closure and restenosis. Abrupt closure refers to the acute occlusion of a vessel immediately after or within the initial hours or days following the dilation procedure. This complication, occurring in approximately one in twenty cases, may result in myocardial infarction and death if blood flow is not quickly restored.
Restenosis refers to the re-narrowing of an artery after a successful angioplasty procedure. Restenosis usually occurs within the initial six months after angioplasty and afflicts approximately one in every two or three cases. Therefore, over one-third of treated patients will require additional revascularization procedures. Many different strategies have been tried to reduce the restenosis rate with mixed results, including mechanical (e.g., prolonged balloon inflations, atherectomy, laser and stenting) and pharmacologic (e.g., calcium antagonists, ace inhibitors, fish oils and steroids) approaches.
One promising new strategy for preventing restenosis is to irradiate the treated section of the coronary artery. Such procedures have been proposed in the past by placing a radiation-emitting source in the coronary artery before or after dilatation. Several of such irradiation procedures are described in, for example, U.S. Pat. Nos. 5,059,166, 5,199,939 and 5,302,168 and PCT Application WO 95/19807. Although a variety of procedures have been proposed for irradiating a treated vessel region, most of such procedures lack the ability to conveniently and safely introduce a radiation source into a treated vessel region, to distribute the radiation source(s) uniformly within the treated vessel region, or to provide the best suited type of radiation to the vessel of the lowest activation level, preferably over a short period of time.
For these and other reasons it would be desirable to provide methods and apparatus which would reduce or greatly eliminate such drawbacks. Such methods and devices should allow for the easy and rapid introduction and withdrawal of the radioactive source and provide for the rapid and uniform irradiation of the treated vessel region.